Protriptyline

Identification

Name

Protriptyline

Accession Number

DB00344 (APRD00441)

Type

Small Molecule

Groups

Approved

Description

Protriptyline hydrochloride is a dibenzocycloheptene-derivative tricyclic antidepressant (TCA). TCAs are structurally similar to phenothiazines. They contain a tricyclic ring system with an alkyl amine substituent on the central ring. In non-depressed individuals, protriptyline does not affect mood or arousal, but may cause sedation. In depressed individuals, protriptyline exerts a positive effect on mood. TCAs are potent inhibitors of serotonin and norepinephrine reuptake. In addition, TCAs down-regulate cerebral cortical β-adrenergic receptors and sensitize post-synaptic serotonergic receptors with chronic use. The antidepressant effects of TCAs are thought to be due to an overall increase in serotonergic neurotransmission. TCAs also block histamine H1 receptors, α1-adrenergic receptors and muscarinic receptors, which accounts for their sedative, hypotensive and anticholinergic effects (e.g. blurred vision, dry mouth, constipation, urinary retention), respectively. See toxicity section below for a complete listing of side effects. Protriptyline may be used for the treatment of depression.

Pharmacology

Protriptyline is a tricyclic antidepressant. It was thought that tricyclic antidepressants work by inhibiting the reuptake of the neurotransmitters norepinephrine and serotonin by nerve cells. However, this response occurs immediately, yet mood does not lift for approximately two weeks. It is now thought that changes occur in receptor sensitivity in the cerebral cortex and hippocampus. The hippocampus is part of the limbic system, a part of the brain involved in emotions. Presynaptic receptors are affected: α1 and β1 receptors are sensitized, α2 receptors are desensitised (leading to increased noradrenaline production). Tricyclics are also known as effective analgesics for different types of pain, especially neuropathic or neuralgic pain. A precise mechanism for their analgesic action is unknown, but it is thought that they modulate anti-pain opioid systems in the CNS via an indirect serotonergic route. They are also effective in migraine prophylaxis, but not in abortion of acute migraine attack. The mechanism of their anti-migraine action is also thought to be serotonergic.

Mechanism of action

Protriptyline acts by decreasing the reuptake of norepinephrine and serotonin (5-HT).

Taxonomy

Description

This compound belongs to the class of organic compounds known as dibenzocycloheptenes. These are compounds containing a dibenzocycloheptene moiety, which consists of two benzene rings connected by a cycloheptene ring.